The present invention relates in general to absorbent structures for electronic equipment and methods of preventing the encroachment of liquids into the electronic circuitry of devices.
In typical usage, various types of electronic devices such as computers, cell phones, remote controls, PDAs, radios, and other electronic articles require human contact and are thus exposed to possible liquid spills and encroachment by rain, and/or water laden vapor including high humidity and fogs, etc. The cost of repairing or replacing electronic circuitry due to liquid compromise, which typically leads to shorts in the system, the failure of keyboard elements, etc., is great when considering that computer keyboards are so prevalent, and their use along with our daily activities, such as in cell phones and laptop computers, is so commonplace. Thus, there has been great interest in a means of protecting such electronic devices from liquid spills.
Most attempts to block liquid spills in electronic devices involve the use of an impermeable liquid barrier that diverts the flow of liquids that should fall into the crevices of a keypad or keyboard. The impermeable barriers in the prior art, such as disclosed in U.S. Pat. No. 5,681,122 involve the use of a tray having walls and a spillway that is located below the external bezel of the computer keyboard but above the electronic equipment, the tray having formations to allow the keys of the keyboard to float through. Spills would then fall into the spaces between the bezel and keys and into the tray, to be collected at the spillway. Other means of protecting electronic devices from liquid spills include such means as disclosed in U.S. Pat. No. 5,491,478, wherein a unitary molded seal membrane is sealed over the top of keys on a cell phone or keyboard keypad, thus directly blocking the flow of spills. A third protection means is a thermal heat seal of a laminated PVC membrane with the electronic traces contained within the seal. This, however, offers only limited water resistance, and breaks down over time.
There are numerous problems with the prior art. The use of such means as a tray requires that the liquid fall downwardly directly into the keypad or keyboard. This does not take into account the encroachment of moisture due to rain, fog, or spills that are substantially non-vertical. The problem with the membrane-type of barrier is that they prevent free and unhindered use of the keypad or keyboard. Further, these membranes typically wear over time and become translucent or even opaque, thus requiring replacement. Since these articles must be fastened securely around the keypad or keyboard, it is not convenient for a typical user to easily replace them. As mentioned above, sealed plastic laminates offer only minimal protection and require thin silver traces, which is subject to corrosion, fatigue, and cracking.
There is thus a need for an improved method of protecting the electronic circuitry in devices such as cell phones, ATM machine keypads, laptop computer keypads, remote controls, PDAs, radios, and other devices where the threat of liquid spill or moisture exposure may be present. This need is heightened by the fact that electronic equipment such as laptop computers, cell phones, phones in phone booths, marine electronic equipment, and other electronic equipment finds more widespread outdoor use.
The present invention addresses such a need.
A method and system of reversibly absorbing liquid penetrations into electronic devices having a body and circuitry is described. The method and system comprises providing an absorbent structure in sheet-like form. The structure contains a hydrogel-forming core within a blown polymer foam, which we refer to as an absorbent sponge membrane. The method and system includes placing the absorbent sponge membrane within the electronic device such that it covers the electronic circuitry to be protected from spills.
A method and system in accordance with the present invention has the further advantage that due to the inclusion of the crystals into the open cells of the sponge, that structure is much easier to manufacture into various templates by punching or stamping holes where the keys and other mechanical obstructions such as bosses and supports must be accommodated.